SACRAMENTO – A six-month investigation of a Rocklin man led to the discovery of a large amount of child pornography on his computer.

Placer County spokesperson Dena Erwin said Peter Terrance Nelson, 41, was arrested Monday night at his Rocklin home. The Roseville Police Department began investigating Nelson in October 2013, which later led to his arrest for videotaping under women's dresses in a Costco store, Erwin said.

Sheriff's detectives searched Nelson's home on April 15 and seized two computers. An ensuing forensics evaluation of the computers determined Nelson had hidden cameras in his residence and filmed numerous females showering and using the bathroom, Erwin said.

Detectives are trying to identify all the women in the collection of videos dating back to 2007. The videos were from Nelson's former residence in Elk Grove and his current home in Rocklin. Detectives also believe Nelson placed cameras in a bathroom at his former place of employment and in portable bathrooms at sporting events, according to Erwin.

Nelson was booked into Placer County Jail and held on bail of $1 million for possession of child pornography.

Placer County Sheriff detectives are asking anyone who was a guest at Nelson's residence in Elk Grove or Rocklin between 2007 and present to contact Detective Hudson at 530-889-7800.